Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 2 is a second image in a sequence thereof;

FIG. 3 is a third image in a sequence thereof; and,

FIG. 4 is a fourth image in a sequence thereof.

The broken lines in the figures serve to illustrate portions of the transitional graphical user interface and form no part of the claimed design.

The dot dash broken line shown in FIGS. 1 through 4 is included for the purpose of showing a display screen or portion thereof and forms no part of the claimed design.

The appearance of the transitional graphical user interface sequentially transitions between the images shown in FIGS. 1-4. The process or period in which one image transitions to another image forms no part of the claimed design. 

CLAIM We claim the ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 